<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    #d1{
        width: 100px  ;
        height: 100px;
       border: 1px solid red;
      /* margin-left: 100px;
      margin-top: 100px;*/
      /*外边距的设置方法*/
      /*margin-bottom:200px;*/
      /*margin-right: 100px;*/
      /*上下相邻添加外边距，取最大值*/
      margin: 10px;
      margin: 10px 20px;
      margin: 10px 20px 30px 40px;
    }
    #d2{
      margin-top: 100px;
      width: 100px;
      height : 100px;
      border: red 1px solid;
    }
    #s1{
      margin-top: 100px;
      /*行内元素，上下外边距无效*/
      margin-right: 100px;
    }
       #s2{
         margin-left: 50px;
         /*左右相邻取外边距俩者是相加的*/
       }
       #big{
         width: 200px;
         height: 200px;
         background-color: green;
         overflow: hidden; /*解决粘连问题*/
       }
       #big>div{
         width: 50px;
         height: 50px;
         background-color: red;
         margin-left: 50px;
         /*当元素的上边缘与上级元素的上边缘重叠时，给元素添加上边距会出现粘连问题*/
         margin-top: 50px;
       }
       #border_div{
         width: 200px;
         height: 200px;
         border: 1px dashed blue;
         margin-bottom: 100px;
         border-radius: 50px;

       }
  </style>
</head>
<body>
<div id="border_div"></div>
<div id="big"><div>
</div></div>
<span id="s1">span1</span><span id="s2">span2</span>
<div id="d1">外边距测试</div>
<div id="d2">div2</div>
</body>
</html>